RESUMO
The present study examined and compared the impact of exercise training on redox and molecular properties of human microvascular endothelial cells derived from skeletal muscle biopsies from sedentary recent (RPF, ≤ 5 years as postmenopausal) and late (LPF, ≥ 10 years as postmenopausal) postmenopausal females. Resting skeletal muscle biopsies were obtained before and after 8 weeks of intense aerobic exercise training for isolation of microvascular endothelial cells and determination of skeletal muscle angiogenic proteins and capillarisation. The microvascular endothelial cells were analysed for mitochondrial respiration and production of reactive oxygen species (ROS), glycolysis and proteins related to vascular function, redox balance and oestrogen receptors. Exercise training led to a reduced endothelial cell ROS formation (â¼50%; P = 0.009 and P = 0.020 for intact and permeabilized cells (state 3), respectively) in RPF only, with no effect on endothelial mitochondrial capacity in either group. Basal endothelial cell lactate formation was higher (7%; P = 0.028), indicating increased glycolysis, after compared to before the exercise training period in RPF only. Baseline endothelial G protein-coupled oestrogen receptor (P = 0.028) and muscle capillarisation (P = 0.028) was lower in LPF than in RPF. Muscle vascular endothelial growth factor protein was higher (32%; P = 0.002) following exercise training in LPF only. Exercise training did not influence endothelial cell proliferation or skeletal muscle capillarisation in either group, but the CD31 level in the muscle tissue, indicating endothelial cell content, was higher (>50%; P < 0.05) in both groups. In conclusion, 8 weeks of intense aerobic exercise training reduces ROS formation and enhances glycolysis in microvascular endothelial cells from RPF but does not induce skeletal muscle angiogenesis. KEY POINTS: Late postmenopausal females have been reported to achieve limited vascular adaptations to exercise training. There is a paucity of data on the effect of exercise training on isolated skeletal muscle microvascular endothelial cells (MMECs). In this study the formation of reactive oxygen species in MMECs was reduced and glycolysis increased after 8 weeks of aerobic exercise training in recent but not late postmenopausal females. Late postmenopausal females had lower levels of G protein-coupled oestrogen receptor in MMECs and lower skeletal muscle capillary density at baseline. Eight weeks of intense exercise training altered MMEC properties but did not induce skeletal muscle angiogenesis in postmenopausal females.
Assuntos
Células Endoteliais , Exercício Físico , Músculo Esquelético , Pós-Menopausa , Espécies Reativas de Oxigênio , Humanos , Feminino , Pós-Menopausa/fisiologia , Músculo Esquelético/irrigação sanguínea , Músculo Esquelético/fisiologia , Músculo Esquelético/metabolismo , Células Endoteliais/fisiologia , Células Endoteliais/metabolismo , Exercício Físico/fisiologia , Pessoa de Meia-Idade , Espécies Reativas de Oxigênio/metabolismo , Microvasos/fisiologia , Microvasos/citologia , Glicólise/fisiologia , Idoso , Receptores de Estrogênio/metabolismoRESUMO
INTRODUCTION: Older individuals and, in particular, individuals at risk of recurrent stroke, may be susceptible to thrombosis when participating in exercise, however, this aspect has not been well investigated. METHODS: Clot microstructure and conventional markers of thrombotic risk were determined in twenty lacunar stroke patients and fifteen healthy age-matched controls before, immediately after and 1 h after a bout of moderate intensity cycling exercise. Data were analyzed using a linear mixed model approach. RESULTS: At rest, clot microstructure (1.69 ± 0.07 vs. 1.64 ± 0.05, corresponding to a difference of ~ 50% in normalized clot mass; p = 0.009) and thrombocyte count (73%; p < 0.0001) were higher, and activated partial thromboplastin time was lower (18%; p = 0.0001) in stroke patients compared to age-matched controls. Acute exercise increased thrombogenic markers similarly in the two groups: incipient clot microstructure (1.69 ± 0.07 vs. 1.74 ± 0.05; p = 0.0004 and 1.64 ± 0.05 vs. 1.71 ± 0.04; p < 0.0001, for stroke and controls respectively), plasma fibrinogen (12%; p < 0.0001 and 18%; p < 0.0001, for stroke and controls respectively) and the combined coagulation factors II, VII and X (p = 0.0001 and p < 0.0001, for stroke and controls respectively). CONCLUSION: The results show that exercise transiently increases the risk of blood clot formation in both stroke patients and controls, however, due to the higher baseline thrombogenicity in stroke patients, the post exercise risk of forming blood clots may be higher in this group. TRIAL REGISTRATION: Registered at ClinicalTrials.gov (NCT03635177).
RESUMO
PURPOSE: Cold-induced vasodilation (CIVD) is a paradoxical rise in blood flow to the digits that occur during prolonged cold exposure. CIVD is thought to occur through active vasodilation and/or sympathetic withdrawal, where nitric oxide (NO) may play a key role in mediating these mechanisms. Beetroot juice (BRJ) is high in dietary nitrate (NO3-) which undergoes sequential reduction to nitrite (NO2-) and subsequently NO. Using a double-blind, randomized, crossover design, we examined the effect of acute BRJ supplementation on the CIVD response in 10 healthy males. METHODS: Participants had a resting blood pressure measurement taken prior to ingesting 140 mL of nitrate-rich BRJ (13 mmol NO3-) or a NO3--free placebo (PLA). After 2 h, participants immersed their hand in neutral water (~ 35 °C) for 10 min of baseline before cold water immersion (~ 8 °C) for 30 min. Laser-Doppler fluxmetry and skin temperature were measured continuously on the digits. RESULTS: Compared to PLA (100 ± 3 mmHg), acute BRJ supplementation significantly reduced mean arterial pressure at -30 min (96 ± 2 mmHg; p = 0.007) and 0 min (94 ± 2 mmHg; p = 0.008). Acute BRJ supplementation had no effect on Laser-Doppler fluxmetry during CIVD (expressed as cutaneous vascular conductance) measured as area under the curve (BRJ: 843 ± 148 PU mmHg-1 s; PLA: 1086 ± 333 PU mmHg-1 s), amplitude (BRJ: 0.60 ± 0.12 PU mmHg-1; PLA: 0.69 ± 0.14 PU mmHg-1), and duration (BRJ: 895 ± 60 s; PLA: 894 ± 46 s). CONCLUSION: Acute BRJ supplementation does not augment the CIVD response in healthy males.
Assuntos
Temperatura Baixa , Dedos/irrigação sanguínea , Nitratos/administração & dosagem , Vasodilatação/efeitos dos fármacos , Estudos Cross-Over , Suplementos Nutricionais , Método Duplo-Cego , Voluntários Saudáveis , Humanos , Fluxometria por Laser-Doppler , Masculino , Temperatura Cutânea , Adulto JovemRESUMO
Physiological strain during exercise is increased by mild dehydration (â¼1%-3% body mass loss). This response may be sex-dependent, but there are no direct comparative data in this regard. This review aimed to develop a framework for future research by exploring the potential impact of sex on thermoregulatory and cardiac strain associated with exercise-induced dehydration. Sex-based comparisons were achieved by comparing trends from studies that implemented similar experimental protocols but recruited males and females separately. This revealed a higher core temperature (Tc) in response to exercise-induced dehydration in both sexes; however, it seemingly occurred at a lower percent body mass loss in females. Although less clear, similar trends existed for cardiac strain. The average female may have a lower body water volume per body mass compared with males, and therefore the same percent body mass loss between the sexes may represent a larger portion of total body water in females potentially posing a greater physiological strain. In addition, the rate at which Tc increases at exercise onset might be faster in females and induce a greater thermoregulatory challenge earlier into exercise. The Tc response at exercise onset is associated with lower sweating rates in females, which is commonly attributed to sex differences in metabolic heat production. However, a reduced sweat gland sensitivity to stimuli, lower fluid output per sweat gland, and sex hormones promoting fluid retention in females may also contribute. In conclusion, the limited evidence suggests that sex-based differences exist in thermoregulatory and cardiac strain associated with exercise-induced dehydration, and this warrants future investigations.
Assuntos
Desidratação , Caracteres Sexuais , Regulação da Temperatura Corporal , Exercício Físico , Feminino , Temperatura Alta , Humanos , Masculino , SudoreseRESUMO
The cytochrome P450-mediated oxidative demethylenation of the benzo-1,3-dioxoles (methylenedioxyphenyl compounds, MDPs), methylenedioxybenzene (MDB), methylenedioxyamphetamine (MDA), and methylenedioxymethamphetamine (MDMA), by rabbit liver microsomes and cytochrome P450IIB4 (CYP2B4) was examined. Material balance studies indicated that demethylenation to catechol derivatives is a major metabolic pathway for MDB, MDA and MDMA. The reactions required NADPH and were inhibited by CO/O2 (4:1, v/v). Biphasic double-reciprocal plots of MDMA, MDA and MDB oxidation suggested participation of more than one isozyme of cytochrome P450 in the reaction. Phenobarbital (PB) induction was selective in that the Vmax values for MDB were increased but not those for MDA and MDMA. Exposure of liver microsomes from PB-pretreated animals to phencyclidine (PCP) markedly suppressed MDB oxidation but had little effect on MDA and MDMA demethylenation. Reconstitution experiments with CYP2B4 demonstrated that MDB is a good substrate for the isozyme; but the relative demethylenation activities for MDA and MDMA were 1 and 2% of that for MDB. These results indicate that the PB-inducible isozymes such as CYP2B4 appear to play an important role in MDB demethylenation, whereas MDA and MDMA oxidation is mediated mainly by constitutive isozymes.
Assuntos
Sistema Enzimático do Citocromo P-450/metabolismo , Dioxóis/metabolismo , Isoenzimas/metabolismo , Fígado/metabolismo , 3,4-Metilenodioxianfetamina/análogos & derivados , 3,4-Metilenodioxianfetamina/metabolismo , Animais , Biotransformação , Cromatografia Líquida de Alta Pressão , Sistema Enzimático do Citocromo P-450/isolamento & purificação , Dioxolanos/metabolismo , Cromatografia Gasosa-Espectrometria de Massas , Isoenzimas/isolamento & purificação , Cinética , Masculino , Microssomos Hepáticos/efeitos dos fármacos , Microssomos Hepáticos/enzimologia , N-Metil-3,4-Metilenodioxianfetamina , Fenobarbital/farmacologia , CoelhosRESUMO
A procedure for the preparation of a cell-free enzyme solution from rice leaves capable of catalyzing the biosynthesis of diterpene hydrocarbons from geranylgeranyl pyrophosphate or copalyl pyrophosphate as added substrates has been developed. The rates of synthesis of a group of "pimaradiene-like" diterpene hydrocarbons are about 75-fold higher with geranylgeranyl pyrophosphate as substrate and about 8-fold higher with copalyl pyrophosphate as substrate in comparison with extracts from untreated control leaves. The maximum rate of diterpene hydrocarbon biosynthesis is seen in extracts prepared at 40 h after uv irradiation. Five diterpene hydrocarbons (compounds A-E) were present in the hydrocarbon fraction biosynthesized from [3H]geranylgeranyl pyrophosphate in large-scale incubation mixtures prepared from uv-treated rice leaves. Three of these diterpenes were identified as ent-kaur-16-ene (B), ent-sandaracopimara-8(14), 15-diene (D), and 9 beta H-pimara-7,15-diene (E) from GC retention times and GC-MS spectral characteristics in comparison with those of authentic reference compounds. Compound C has spectral characteristics analogous to those of a pimaradiene, but a specific structural assignment from the data available was not possible. Similar incubations with [3H]copalyl pyrophosphate as the substrate and enzyme prepared from uv-treated rice leaves produced ent-kaurene (B), ent-sandaracopimara-8(14),15-diene (D), and compound C, but not 9 beta H-pimara-7,15-diene (E). These results are consistent with a proposed biosynthetic scheme in which 9 beta H-pimara-7,15-diene serves as a precursor of the momilactone family, and ent-sandaracopimara-8(14),15-diene serves as a precursor of the oryzalexin family of rice phytoalexins. ent-Kaurene was the only diterpene detected in incubation mixtures containing enzyme extract from untreated rice leaves and [3H]copalyl pyrophosphate as the substrate. It is suggested that kaurene biosynthesis in rice leaves is probably associated with gibberellin biosynthesis and the regulation of vegetative growth rather than stress metabolism. The diterpene cyclization enzymes in extracts of uv-treated rice leaves show only a relatively modest inhibition by the plant growth retardants AMO-1618 and Phosfon D. No evidence was obtained for the subcellular localization of these cyclization enzymes in organellar preparations; it is tentatively concluded that the enzymes are present predominantly in the extraorganellar cytoplasm of rice leaves.